I am looking for a drawing or close-up photo of the safety trip-cocks fitted to ex-GWR engines working over London Transport electrified lines, please. Images culled from the internet are tantalisingly hazy...

Just to throw another pebble in the pond, would GWR steam locos working through the Met tunnels to the GWR depot at Smithfield (including possibly also the H&C for coal trains) have been fitted with trip-cocks, as well as condensing gear, from quite early on? (Possibly from electrification of the Circle in 1905?)

I don't have a start date, Martin, but the condensing 97XX were introduced in 1933, following a conversion of an earlier loco in 1931, and had trip-cock apparatus from new, which suggests to me that their predecessors had it as well. Incidentally, a few Fowler 0-6-0T were so fitted, to work coal trains to the ex-MR coal yard at High Street Kensington, accessed via the Metropolitan, and must have had predecessors. I understand that some LNER locos were so fitted as well, for working on LT lines in east London. The traffic worked by the latter lasted into the diesel era, so some of those were so fitted as well.

Noel wrote:I don't have a start date, Martin, but the condensing 97XX were introduced in 1933, following a conversion of an earlier loco in 1931, and had trip-cock apparatus from new, which suggests to me that their predecessors had it as well. Incidentally, a few Fowler 0-6-0T were so fitted, to work coal trains to the ex-MR coal yard at High Street Kensington, accessed via the Metropolitan, and must have had predecessors. I understand that some LNER locos were so fitted as well, for working on LT lines in east London. The traffic worked by the latter lasted into the diesel era, so some of those were so fitted as well.

Some of the lner locos would have come from the metropolitan railway when they changed how they operated and sold parts to the lner. Other locomotives that didn't pass to the lner would have been used by lt for engineering or the small amount of goods traffic they still handled such as tip trains for rubbish and spoil. Any former met locomotives would have gained L numbers.

The LT panniers differed from the standard gwr ones by having their rain strips on the cab roof being moved to the side due to tunnel clearance issues. Obviously they'd have also had trip cocks. The replacement for the panniers, diesel locomotives had a shunting truck coupled as they were too short without to operate the trip cock system. Judith edge do a suitable kit for the diesels.

I've been looking at the system with my research partner as at some point I'd like to model parts of lillie bridge depot, initially as a diorama I expect.

The ex-Metropolitan locos went to the LNER in 1937 (together with most of the goods wagons), but the LPTB retained sufficient small tank engines to work service trains through the Met tunnels, and sufficient wagons to cater for the needs of the PW Department.

I am under the impression that the larger tank engines (H Class 4-4-4T and K Class 4-6-2T) would never have worked through the Met tunnels, and the LNER would have kept these either for passenger trains between Rickmansworth and Aylesbury (H Class engines) or the goods trains out to Aylesbury (K Class engines), or would have transferred them away to other parts of the LNER.

Prior to their transfer to the LNER, these engines could have worked over electrified lines between Baker Street and Harrow (1905 - 1925) and between Harrow and Rickmansworth (1925 - 1937), but I don't know whether or when they would have been fitted with trip-cocks. After the introduction of the Bo-Bo electric locos, loco-hauled stock was steam-hauled only from Harrow (until 1925) and then from Rickmansworth (after 1925).

Steam working by GWR locos over the Circle/Widened Lines/Hammersmith and City after electrification in 1905 would have included goods/coal trains to Hammersmith, and meat van trains to Smithfield. Small tank engines (Metro Tanks, Panniers, etc.) were fitted with condensing gear for this purpose, and it is these engines which were presumably also fitted with trip-cocks.

The LNER locos and their successors I was thinking of would have been those working to New Cross and Poplar over the East London line from Shoreditch and Whitechapel, the connections to which have long since been cut, and those working from Bow to the Tottenham and Forest Gate Joint over the Metropolitan/LT&SR line, until the LT and BR traffic was segregated in the early 1960s.

A LURS article on safety devices suggests that the tripcocks first appeared on MDR A-stock in 1903 and rapidly became standard. Therefore, one would expect them on GWR 633 class and Metros working over the inner circle to Smithfield from c.1905. AFAIK, the Widened Lines were not protected in this way (corrections, anybody?).

Tripcocks were required on the widened lines and post steam were fitted to the diesels working there, 23, 24, 31 etc.Also required for the Hammersmith and City and 3 2251 class locos had tripcocks for that.Trains running into Paddington Suburban (platforms 13 - 16) also required tripcocks which would have included panniers and later the 117 DMUsThen there were freights on the Central line, Leyton outwards till 1962 where the ER needed tripcock fitted J15s.And Cricklewood had fitted Jintys to run from Brent To High St Ken.Regards

What a fascinating harvest of information - thanks to all who have replied so far here.

Keith has hit the nail on the head, for my case - it is the Paddington suburban platforms, and hence the fitting of tripcocks to some Class 61xx locos that is relevant to my build. I have now gleaned a good number of photos from the web and my (very limited) GWR library, so the first of a pair of model versions is well advanced now.